Features and the data formats that back many features will continue to change until beta. Beta should happen before gold. That means previous alpha's worlds usually won't load. The simple way to lock in and not break your worlds is to not update the game, which would be similar to us saying hey we are done now and everything in the future is 7dtd 2.
Now if you locked in to a version, you would be missing all the new features. Like the massive pile of new block shapes coming in A20 and shape UI that goes with it.
I'd prefer new zombies not act like old zombies, since then it is just a reskin, which is boring.
Maybe, but not planned.